1. Field of the Invention
The present invention relates generally to a downhole device that may be used to divert fluid out of a work string and into the annulus between the work string and the tubing or casing. The downhole device may be located at any point along a work string at which it may be necessary to divert the fluid flow to the annulus. The downhole device may be activated and deactivate inserting a single dart into the work string. The device catches the dart, which blocks the fluid flow through the work string. The increased fluid pressure due to the blocked flow path activates the device, which diverts the fluid flow out of the work string into the annulus. The increased fluid pressure moves a circulating sleeve within the device to align fluid ports allowing fluid flow into the annulus. A locating sleeve with a continuous j-track allows the device to be retained in activated position. The dart is adapted to deform under a predetermined amount of fluid pressure, thus passing the dart past the device and returning fluid flow through the work string. The downhole device may be activated multiple times without removing the downhole device from the wellbore.
2. Description of the Related Art
In the oil and gas industry long tubular work strings are often used in drilling, completion, displacement, and/or work over operations. Often the work string is used to carry fluid down the well to a tool located at the end of the work string. For example, fluid may be circulated down a work string and out of a drill bit located at the end of the work string. Often drilling mud is pumped down the work string and through the drill bit. The drilling mud acts as a lubricant, but also carries the drill cuttings up the annulus around the work string to the surface.
Under certain circumstances it may be desirable to circulate fluid into the annulus surrounding the work string at a particular location. For example, the drilling mud may be entering into a porous well formation instead of properly circulating the drill cuttings to the surface. In this instance, it may be necessary to inject a sealing agent into the formation in an attempt to prevent the future loss of mud into the formation. A number of systems have been disclosed that enable the circulation of fluid to the annulus without having to remove the work string from the well bore.
U.S. Pat. No. 4,889,199 discloses a downhole device that allows annular circulation after dropping a plastic ball into the work string. The work string is broken at the surface and a plastic ball is dropped into the work string. The work string is then reconnected and fluid is pumped into the work string until the ball reaches the downhole device. The downhole device includes a shoulder that is adapted to catch the ball within the work string. Once seated on the shoulder the ball blocks the fluid flow through the work string and continual pumping of fluid causes fluid pressure to build above the seated ball. The device includes a ported sleeve that is adapted to move within the device. The sleeve is biased to an initial position by a spring. Once the force on the ball due to the fluid pressure is greater than the spring force, the ported sleeve moves within the device such that ports in the sleeve align with exterior ports in device allowing fluid to be circulated out of the work string into the annulus. When the sleeve is in its initial position the exterior ports in the work string are sealed preventing fluid flow to the annulus.
To remove the ball from the shoulder in the device, a number of smaller steel balls must be dropped into the work string, which again requires that the work string be disconnected at the surface. The number of steel balls inserted into the work string must be equal to the number of annular ports in the sleeve. The work string is then reconnected and fluid is pumped until the steel balls reach the downhole device. The steel balls are sized such that they fit within the sleeve ports blocking the fluid flow to the annulus. With the fluid flow to the annulus blocked by the steel balls and the fluid flow through the work string prevented by the plastic ball, the fluid pumped into the work string causes the fluid pressure within the work string to increase above the device until the plastic ball is deformed and pushed past the shoulder. The deformed plastic ball falls into a housing located at the bottom of the device. This allows fluid to once again flow through the work string past the device and the steel balls, which are sized smaller than the plastic ball, pass the shoulder and also are captured in the housing below the device. The sleeve is returned to its initial position due to the biasing spring until the next plastic ball is inserted into the work string.
While the disclosed device does provide for annular flow out of the work string it requires that the work string be broken each time fluid flow is diverted out of the work string and each time fluid flow is returned. This process causes increases in well services costs as well as providing multiple opportunities for operator error. Further, the disclosed device requires the use of multiple balls on each cycle. These balls accumulate below the device in the housing or alternatively are dropped into the well. The large number of balls requires a rather large housing or alternatively requires that the device be brought to the surface frequently to remove the passed balls.
The use of a plastic ball may make it difficult for operators or well service providers to accurately predict the amount of fluid pressure required to pass the ball past the shoulder within the device. The temperature within the well may cause the plastic ball to be a different size than at surface temperatures. The temperature within the well may also cause the dimensions of the shoulder to change, but because the shoulder is not comprised of plastic the change in shape may not correlate with the changes reflected in the ball. This may further make it difficult to predict the fluid pressure necessary to pass the plastic ball past the shoulder.
In light of the foregoing, it would be desirable to provide a tool and method to divert fluid flow out of a work string during which the work string would only have to be broken to divert and restore fluid flow. It would further be desirable to provide an annular flow diverting device that used a device that would deform under a predetermined amount of fluid pressure. It would also be desirable to provide a tool and method that only required one dart to be dropped into the work string to divert fluid flow and for which the fluid flow could be restored without the need of an additional dart.
The present invention is directed to overcoming, or at least reducing the effects of, one or more of the issues set forth above.